Matt, you'll probably need to get that body mount bolt from Toyota. It's a specialty bolt.

For your wheel question, I would say to get some 15x8 white wagon wheels - pretty common (see many pictures of mine in the link in my sig line) and allow you to run wider tires than the stock 15x5.5s. If you want to go to 16s you'll just have to find one out there that has the right backspacing and is the style you want. The only stock option is a split rim from Oz. I don't think I've ever seen a wagon wheel in a 16" size - might have to do some googling...

I found some non USA FJ60 16s. $190 each after club discount from Boulder Toyota, needless to say, I'm exploring other options. I have a newish set of 275/70/16s I wanted to put on, but maybe I'll try to trade them or sell them. Or maybe I'll run spacers and tacoma wheels. Or maybe... I'm also going to redo all the body mounts this weekend, then reassemble, and drive it. I'll 'fix' the floorpan issues after the newness wears off. I'm already regretting not driving it around.

With where your exhaust is dumping, I'd check your steel right above there when you get some free time. My exhaust is set up the same way and I have convenient ground viewports through the body in that spot.